| Year | Value | | 2015 | 4.610960544994 | | 2014 | -196.24133197657 | | 2013 | -213.04915732858 | | 2012 | -210.75137818631 | | 2011 | -218.43168433893 | | 2010 | -213.7812484042 | | 2009 | -193.3715112941 | | 2008 | -184.52031768282 | | 2007 | -162.03834818442 | | 2006 | -165.5421165995 | | 2005 | -172.34360788608 | | 2004 | -178.24747496039 | | 2003 | -171.98045209793 | | 2002 | -166.37488775893 | | 2001 | -161.28746503869 | | 2000 | -169.43229045555 | | 1999 | -159.84806650839 | | 1998 | -152.49858436744 | | 1997 | -152.88166462249 | | 1996 | -138.36764188876 | | 1995 | -150.05546601151 | | 1994 | -147.32141482522 | | 1993 | -144.36721064465 | | 1992 | -145.73555296005 | | 1991 | -136.36832880178 | | 1990 | -137.33763612397 | | 1989 | -195.57198152639 | | 1988 | -182.62489325975 | | 1987 | -189.79709531126 | | 1986 | -198.97333366778 | | 1985 | -203.04780344422 | | 1984 | -226.51889236267 | | 1983 | -217.60495645753 | | 1982 | -229.48060262641 | | 1981 | -274.15904847924 | | 1980 | -362.8400162409 | | 1979 | -388.24184273826 | | 1978 | -430.55254445227 | | 1977 | -452.60904961965 | | 1976 | -470.92808147658 | | 1975 | -441.88984896413 | | 1974 | -456.75448753425 | | 1973 | -448.67411480764 | | 1972 | -448.74362121484 | | 1971 | -433.78659318929 | | 1970 | 54.34614762246 | | 1969 | 57.043977378239 | | 1968 | 65.516286270056 | | 1967 | 66.240658022377 | | 1966 | 68.761221078066 | | 1965 | 69.591100629738 | | 1964 | 68.167416614928 | | 1963 | 69.710019248836 | | 1962 | 69.217356666274 | | 1961 | 69.75669076459 | | 1960 | 72.127727974814 |
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